The present invention relates to a temperature control capable of always keeping an object at a fixed temperature.
A typical example of a prior art temperature control involves employment of bimetal material whereby a mechanical contact is opened or closed to control power supply to a heater. It is also well known to use a temperature sensor such as a thermistor or a positive temperature characteristic thermistor to keep an object at a desired temperature.
These prior art temperature controls generally comprise a heating element adapted to heat an object and a temperature sensor (for example, a bimetal and a thermistor) adapted to control power supply to the heating element. A feed-back loop including the temperature sensor controls power supply to the heating element and keeps the object at a given temperature. Nevertheless, it is almost difficult to accurately maintain the object at the desired temperature because substantial heat resistance is present between the heating element and the object. A temperature increase or decrease in the object and even temperature detection will be timed-delayed due to the heat capacity of a heat transmission medium and the object and the heat resistance of the heat transmission medium. This makes a control system unstable and the gain of the control system relatively lower.